武夷山西坡成矿花岗岩的蚀变分带及地表矿化标志特征

该文着重介绍了武夷山西坡主要与锡矿化有关的成矿花岗岩的蚀变类型、蚀变分带、蚀变带矿物组成、标志矿物及化学成分等特征，同时还指出了不同矿床类型地表矿化标志的差异。

金川二矿区西主井地表矿仓施工的几项技术措施

本文介绍了金川西主井在施工中所采取的双圈梁吊盘和整体移动钢管凿井井架等主要技术措施的应用经验.

控制点布设方案对无人机精度测量的影响及其应用--以西北地区某尾矿坝地表沉降监测为例

近年来矿区地质灾害愈发严重。为准确监测尾矿坝地表沉陷变形,以地形地貌复杂的尾矿坝为研究实例,开展无人机低空摄影的形式进行监测数据收集。无人机原始POS数据存在系统误差的问题,文章利用误差改正模型纠正原始POS数据,并设计7种像控点布设方案,并对获取的尾矿坝高分辨率正射影像及DEM进行了精度评价。结果显示,当布设像控点数量为8个时,数据误差可以控制在3 mm以内;用两期DEM数据差值覆于地面模型,生成尾矿坝沉降图,沿Y=350 m、Y=100 m和X=60 m剖面线做剖面图。基于测量结果发现,尾矿坝已出现整体沉降,其中南部尾矿坝下坡沉降范围最大,沉降范围在0.16 m之内。这次应用验证了在尾矿坝地表监测中无人机低空摄影测量的精度是可靠的。利用无人机的高精度成图方法对尾矿坝变形进行监测,对应急响应溃坝可能导致的绿洲地区及周边河湖生态灾难地形和矿区安全生产起到一定的预警作用。

云南镇沅黄草岭铅锌矿控矿因素及成因分析

矿区位于兰坪-普洱中生代前陆盆地南端,景星组下段上部浅色细碎屑岩夹钙锰质层为赋矿岩层,矿床严格受断层及破碎带控制,属典型的沉积改造中低温铅锌矿床。

Ground subsidence induced by pillar deterioration in abandoned mine districts

When roadways are constructed above or adjacent to heavily mined regions, the ground subsidence caused by pillar collapse inflicts severe damage on these roadways. In this study, some surface subsidence events were first reviewed to present roof caving characteristics caused by pillar failure. The bearing characteristic and failure pattern of a single pillar with or without effect of discontinuity were further numerically simulated using distinct element code(3 DEC). It was found that the spalling of pillar or slippage of discontinuity would damage the bearing capacity of pillar during the failure process. The stress at the pillar core could be greater than uniaxial compressive strength of the pillar. However, when a discontinuity runs through a pillar, the slippage of discontinuity would significantly degrade the bearing capacity of the pillar. In pillar support system, if any pillar unexpectedly degrades or loses its bearing capacity, the load transferred from the degraded pillar acts on neighboring pillars, and the shear force also increases at relevant positions. However, the roof cutting and surface subsidence characteristics would perform in different patterns. In some cases, surface subsides slowly;in the worst scenario, shock bump may be induced by pillar and roof collapse.

A new approach to predicting mining induced surface subsidence

There are many parameters influencing mining induced surface subsidence. These parameters usually interact with one another and some of them have the characteristic of fuzziness. Current approaches to predicting the subsidence cannot take into account of such interactions and fuzziness. In order to overcome this disadvantage, many mining induced surface subsidence cases were accumulated, and an artificial neuro fuzzy inference system(ANFIS) was used to set up 4 ANFIS models to predict the rise angle, dip angle, center angle and the maximum subsidence, respectively. The fitting and generalization prediction capabilities of the models were tested. The test results show that the models have very good fitting and generalization prediction capabilities and the approach can be applied to predict the mining induced surface subsidence.

MECHANISM OF WATER-SOIL COUPLED ACTION DURING MINING SUBSIDENCE

This paper,on the basis of the scientific research of engineering geological exploration in a mining area,systematically studies the reasons and influence factors of consolidation and deformation of the saturated soil included in the thick loose water-bearing overburden due to mining subsidence,and analyses the dissipation of hyperstatic pore water pressure during the change of original stress and strain state of the soil. Again,by means of the coupled model based on Cambridge model and Biot's three-dimensional consolidation theory,adopting a great many physico-mechanical parameters measured in various soil layers,the paper analyses the consolidation and deformation of saturated soil affected by mining subsidence with elasto-plastic finite element method.Thus,the research not only reveals the regulation of stress,strain,displacement and hyperstatic pore water pressure dissipation in overlying soil mass,but also opens up a new direction and way for the research of mining subsidence.

Stability and reliability of pit slopes in surface mining combined with underground mining in Tonglushan mine

Slope stability is of critical importance in the process of surface-underground mining combination. The influence of underground mining on pit slope stability was mainly discussed, and the self-stabilization of underground stopes was also studied. The random finite element method was used to analyze the probability of the rock mass stability degree of both pit slopes and underground stopes. Meanwhile, 3D elasto-plastic finite element method was used to research into the stress, strain and rock mass failure resulting from mining. The results of numerical simulation indicate that the mining of the underground test stope has certain influence on the stability of the pit slope, but the influence is not great. The safety factor of pit slope is decreased by 0.06, and the failure probability of the pit slope is increased by 1.84%. In addition, the strata yielding zone exists around the underground test stope. The results basically conform to the information coming from the field monitoring.

Distribution of heavy metals in the topsoil of the Jining mining area

The geochemical baseline is the fundamental reference for environmental change and assessment.In this article we describe cluster and regression analyses with a normalization procedure.The elements Sc and Ag were chosen to calculate the environmental geochemical baseline.The geoaccumulation index was calculated and mapped to indicate the environmental quality of the soil.The results show that the urban areas are barely polluted with Ni and Cr but the rural areas in the southern part of the city, and the western part of the lake,are polluted with Ni,Cr,and Cu at the second level.On the other hand,the rural areas in the southern part of the city,and the western part of the lake,are polluted with As at a moderate level.The other area is polluted at the second level.An increase in As pollution occurs in a direction from northeast to southwest.The Cd pollution follows a trend similar to As,with an additional smaller contaminated area polluted at levelⅢ.The Hg pollution typical of urban areas occurs in the main and northern parts of the city.The geochemical accumulation index decreases from the city center to the periphery.The highest pollution level reaches levelⅣ,which indicates that the soil is seriously polluted with Hg.The southern part of the city and the rural areas to the west of the lake are not contaminated with Hg.Geological factors and the disturbance from human activities are both possible major factors:further research is needed to identify them.

EXPERIMENTAL RESEARCH ON EFFECTS OF INITIAL JOINTS ON SURFACE DISPLACEMENT DUE TO COAL MINING

Surface displacement caused by underground coal mining is influenced by many factors such as the depth and thickness of the coal seam and joints in overburben rocks. Extensive efforts have been devoted to the ground surface displacement. Nevertheless, the joints have not been taken into consideration for a long time. In fact, there exist numerous joints and cracks in rocks.As a result, the joints in overburden rocks have to be taken into account. The joints in rocks can be treated as initial damage theoretically. In this paper, two kinds of physical model, one containing no initial joints and anotber containing some initial joints, are employed to systematically investigate effecs of initial joints on surface subsidence. Moreover, within the framework of damage mechanics, the statistical relationships between the characteristic value for surface displacement and damage variable are obtained.

Ground movement mechanism in tectonic stress metal mines with steep structure planes

When mining metal mines with steep structure planes by the caving method,there is a mechanical model in which the horizontal stress on the rock mass is simplified as a column before surface subsidence.The model is used to deduce critical support load and limiting column length for a given horizontal stress and support pressure.Considering the impact of the column effect,a method is proposed to determine the movement of the ground and caving area in a mine.After surface subsidence,the horizontal stress on a surrounding rock mass can be simplified to a cantilever beam mechanical model.Expressions for its bending fracture length are deduced,and a method is given to determine its stability.On this basis,an explanation for the large ground movement and subsidence scope was given.A case study shows that the damage effect of column and cantilever beam is significant for ground movement in metal-ore mine,and an appropriate correction value should be applied when designing for its angle of ground movements.

Characterization of the Gold Ore to Acquire an Optimum Degree of Liberation

Gold ore processing is often ineffective in obtaining gold metal. Various methods have been successfully developed on an industrial scale, but small-scale gold mines are often problematic. The problem of inefficiency of processing is caused by gold ore characterization and evaluation of gold ore preparation process is not implemented. In this study, the conditions of gold ore deposits have a thin thickness （vein）. These gold ore deposits have an economic value if they are developed by traditional gold mining. The objective of the research is to identify and characterize gold ore as well as to analyze the optimum condition to obtain the perfect gold mineral liberation degree. Research methods include characterization of gold ore geology, sampling for test preparation using rod mill （amalgamation）, gold mineral liberation using time variables and number of rods. After the grinding process, grain size analysis is performed with various mesh sizes, and the analysis of each fraction uses a polarization microscope. The results show that gold ore minerals are associated with pyrite, chalcopyrite, galena and gangue minerals. Gold minerals are fully liberated at a certain size. The results of this research are very useful for the gold ore grinding process to obtain an efficient gold processing.

Time series prediction of mining subsidence based on a SVM

In order to study dynamic laws of surface movements over coal mines due to mining activities,a dynamic prediction model of surface movements was established,based on the theory of support vector machines(SVM) and times-series analysis.An engineering application was used to verify the correctness of the model.Measurements from observation stations were analyzed and processed to obtain equal-time interval surface movement data and subjected to tests of stationary,zero means and normality.Then the data were used to train the SVM model.A time series model was established to predict mining subsidence by rational choices of embedding dimensions and SVM parameters.MAPE and WIA were used as indicators to evaluate the accuracy of the model and for generalization performance.In the end,the model was used to predict future surface movements.Data from observation stations in Huaibei coal mining area were used as an example.The results show that the maximum absolute error of subsidence is 9 mm,the maximum relative error 1.5%,the maximum absolute error of displacement 7 mm and the maximum relative error 1.8%.The accuracy and reliability of the model meet the requirements of on-site engineering.The results of the study provide a new approach to investigate the dynamics of surface movements.

The research progress and prospect for the technology of controlling surface subsidence by grouting separated layer in overburden at coal mines in China

The developed process and theoretical achievement for the technology of controlling surface subsidence by grouting separated layer in overburden is summarized in this paper. The research progress of the technology is discussed synthetically on the basis of practice and research results obtained at coal mine of China in recent years. According to the development tendency of mining under buildings, water bodies and railroads and the properties of the technology, the future research direction is proposed.

Surface Movement Regularity of Super-Wide Mining Face With Top-Coal Caving

No.4326 super-wide panel of Wangzhuang Coal Mine ( in which the fully-mechanized top-coal caving longwall mining method was used) was monitored for dynamic characteristic of surface movement. The dynamic surface movement in and after mining was predicted by using the Mining Subsidence Prediction System. The results indicate that after mining, the surface above the super-wide panel reaches a state of full subsidence, making the No.309 national highway above the panel be located on the flat bottom of the subsidence basin so that the influence of mining activity in both sides of 4326 panel on the national highway is the smallest.

An investigation of surface deformation after fully mechanized,solid back fill mining

The surface deformation after fully mechanized back filling mining was analyzed.The surface deformation for different backfill materials was predicted by an equivalent mining height model and numerical simulations.The results suggest that:(1) As the elastic modulus,E,of the backfill material increases the surface subsidence decreases.The rate of subsidence decrease drops after E is larger than 5 GPa;(2) Fully mechanized back fill mining technology can effectively control surface deformation.The resulting surface deformation is within the specification grade I,which means surface maintenance is not needed.A site survey showed that the equivalent mining height model is capable of predicting and analyzing surface deformation and that the model is conservative enough for engineering safety.Finally,the significance of establishing a complete error correction system based on error analysis and correction is discussed.

Study on the offset of inflection point about probability function method

In this paper, rock mass is regarded as anisotropic clastic units and the partial differential equation of subsidence has been testified. The solution about homogeneous anisotropy has been obtained. The existence of inflection point offset in subsidence formula has been proved. Lastly, the relevant influence factors about the offset of inflection point have been simply discussed.

Influence of drainage of aquifer on settling of ground surface in mining area with high ground water level

Based on the basic principles of hydrogeology and soil mechanics, studied thegenesis mechanism and control factors of settling of ground surface caused by the drainageof the aquifer in the construction of coal mines, and put forward a corresponding calculatingmodel demonstrated by practical example.The study provides mining areas,which are covered with a very thick Quaternary soil layer and abundant ground water, witha theoretical basis aimed at forecasting the settling of ground surface.